Postoperative atrial fibrillation in emergent non-cardiac surgery: Risk factors and outcomes from a ten-year intensive-care unit retrospective study

BACKGROUND Atrial fibrillation (AF) represents a common arrhythmia with significant implications and may occur pre-, intra-, or postoperatively (POAF). After cardiac surgery POAF occurs in approximately 30% of patients, while non-cardiac/non-thoracic surgery has a reported incidence between 0.4% to 15%, with new onset POAF occurring at a rate of 0.4% to 3%. While AF has been extensively studied, it has not been well described in emergent non-cardiac surgery associated with increased surgical stress in an intensive care unit setting (ICU). AIM To investigate the incidence/predictors of POAF in emergent non-cardiac surgery and its associations with postoperative outcomes in the ICU. METHODS This retrospective study included patients ≥ 18 years who underwent exploratory laparotomy or lower extremity amputation between October 2012 and September 2023 and were admitted in the ICU. Data of interest included occurrence of POAF, demographic characteristics, comorbidities, laboratory values, administered fluids, medications, and postoperative outcomes. Statistical analyses consisted of identifying predictors of POAF and associations of POAF with outcomes of interest. RESULTS A total of 347 ICU patients were included, 16.4% had a history of AF, 13.0% developed POAF, and 7.9% developed new-onset POAF. Patients with new-onset POAF were older (79.6 ± 9.1 vs 68.1 ± 14.8 years, < 0.001), of white race (47.8% vs 28.8, P < 0.001), hypertensive (87.0% vs 71.2%, P = 0.011), had longer ICU length of stay (ICU-LOS) (13.4 vs 6.7 days, P = 0.042), higher mortality (43.5% vs 17.6%, P = 0.016) and higher rate of cardiac arrest (34.8% vs 14.6%, P = 0.005) compared to patients without new-onset POAF. Multivariable analysis revealed increased POAF risk with advanced age (OR = 1.06; 95%CI: 1.02-1.10, P = 0.005), white race (OR = 2.85; 95%CI: 1.26-6.76, P = 0.014), high intraoperative fluid (OR > 1; 95%CI: 1.00-1.00, P = 0.018), and longer ICU-LOS (OR = 1.04; 95%CI: 1.00-1.08, P = 0.023). After adjusting for demographics, new onset POAF significantly predicted mortality (OR = 3.07; 95%CI: 1.14-8.01, P = 0.022). CONCLUSION POAF was associated with prolonged ICU-LOS, white race, and high intraoperative fluid. New-onset POAF was associated with increased risk of cardiac arrest and death in critically ill patients.